This is what I was going to suggest. Many people in my training class don't give their dogs lunch before class (it's 1:00pm on Saturdays), and they bring the dog's lunch portion to class for "treats." It's basically just making them work for their regular meal, but it works because the dog is hungry. This sounds like a really good option for you!

You've gotten some really good suggestions on here and I think they will help you out. I hope this doesn't offend, but I just want to add that IMO you should be careful not to project your past issues onto your dogs. Dogs only get fat with help from humans. You have the ultimate control over that. If treats will help you train them, you have control over what those are. GRs want to please and they want to eat. Not sure if they motivated more by pleasing or food. LOL. But, just be sure that you are using all the options available to you to turn your dogs into the best they can be. (Sorry if this is out of line. BTW, I have the greatest admiration for people who've taken charge of their health the way you have.)

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Kathleen, mom to one human, age 17, three canines, and a bunch of fish.